The present invention relates generally to optical disc data storage systems. More specifically, the present invention relates to a slider for use in an optical head gimbal assembly of an optical disc data storage system.
Optical data storage disc systems are a promising technology for storing large quantities of data. The data is accessed by focusing a laser beam onto a data surface of the disc and detecting light reflected from or transmitted through the data surface.
In general, in optical storage systems, data is in the form of physical or magnetic marks carried on the surface of the disc which are detected using the reflected laser light. There are a number of different optical disc technologies which are known in the industry. For example, compact discs are currently used to store digital data such as computer programs or digitized music. Typically, compact discs are permanently recorded during manufacture. Another type of optical system is write-once read-many (WORM) systems in which a user may permanently write information onto a blank disc. It is also desirable to provide a system which is erasable, such as phase change and magneto-optic (M-O) systems. Phase change systems detect data by sensing a change in reflectivity. M-O systems read data by measuring the rotation of the incident light polarization due to the storage medium.
High density optical recording, particularly for near-field recording (i.e., M-O or phase change systems) typically requires an optical head gimbal assembly (OHGA) for carrying the transducing device over the data surface of the optical media. The OHGA includes a slider which "flies" proximate the data surface of the optical disc as the disc rotates at a high speed. An actuator is used to radially position the slider over the disc surface. U.S. Pat. No. 5,497,359 shows an example of a slider for use with an optical disc data storage system.
Optical disc data storage systems which use the "near field" (or evanescent field) include a Solid Immersion Lens (SIL). Such near field technology is shown in U.S. Pat. No. 5,125,750 to Corle et al. which issued Jun. 30, 1992 entitled "OPTICAL RECORDING SYSTEM EMPLOYING A SOLID IMMERSION LENS" and in U.S. Pat. No. 5,497,359 to Mamin et al. entitled "OPTICAL DISC DATA STORAGE SYSTEM WITH RADIATION-TRANSPARENT AIR-BEARING SLIDER" which issued Mar. 5, 1996. Typical SIL structures include a hemispherical lens cap positioned on a top side of the slider and an optical mesa structure positioned on the air bearing side of the slider. The optical mesa must be positioned very close to the data surface of the optical disc in order for their to be near field optical coupling. Typically this is on the order of less than a few wavelengths.